Is this normal???

[Drnick]

4.5 mercruiser had manifold overheating alarm
this has been posted before, bought new manifolds
and risers with new poppet valves, just installed and ran motor
all looks good, but, used thermal sensor, and starboard
was 195 and port was 156, I have no idea why there is
such a difference between the two!! PS I was running
on garden hose and muffs during this test, and engine temp was normal.

 

[Rick Stephens]

Just the way she flows. Better to check after running for a while on the water, even then they'll be different. Kind of surprised you can get either up over 160 though.

 

[Bondo]

I have no idea why there is such a difference between the two!!

Ayuh,..... They're Never the same,......

The radical difference could be how it sits on the wagon, or the lay of the land under it,.....

 

[muc]

This is a catalyst motor.
you have something wrong.
When you replaced the poppets and springs are you sure you got the right ones? There are 3 different setups and a design 1 and design 2 systems.
Do you have vessel view on this boat?
when you replaced the manifolds and risers are you sure you got the right gaskets?
Maybe post a serial number so I can see exactly what you have.
Has anybody hooked up diagnostic software to this?
What were your port and stbd equivalency ratios under load?
Have you had a dealer look at this? If not, find a dealer with a MerCruiser Master Technician. Call different dealers until you find one. This designation is not bulls**t. We had to pass the certification test with a higher score and then take another closed book test to get that plaque that hangs on the wall. Ask to see it and make sure it’s current.

Edit: see that you have a few other posts about this problem. It's getting late tonight, I'll try to look at them tomorrow.

 

[Drnick]

Thanks amtech, did a water test,(the only way to get a proper
reading) both manifolds were between 10 degrees of each other, on average 150 F .PS next boat ( ha ha) will be an outboard!